Command "istats" gives "-bash: istats: command not found" after "gem install iStats"

Solution 1:

Thanks to historystamp's comment here is how the problem was solved (for bash shell):

1. Open/Launch Terminal
2. gem uninstall iStats (source)
3. gem install iStats --user-install (source)
4. export PATH="~/.gem/ruby/2.6.0/bin:$PATH" (source)
5. source ~/.bash_profile (source)
6. istats

If you use macOS Catalina, the default shell is zsh. The adapted instructions are the following:

1. Open/Launch Terminal
2. gem uninstall iStats (source)
3. gem install iStats --user-install (source)
4. Open or create ~/.zshrc
5. At the end of the file (or where appropriate) insert: export PATH=~/.gem/ruby/2.6.0/bin:$PATH (source)
6. Save file ~/.zshrc
7. Source the .zshrc file: . ~/.zshrc (source)
8. istats